So, my PCs are heading through the wilderness and they know there's a bounty hunter out there looking for them, and they try to lead him astray. They roll their Deception check - difficulty provided by the Bounty Hunter's stats - and fail. So the players know that they haven't managed to mislead the Bounty Hunter. But there's no way the characters could have known this information at the time: in fact, they wouldn't know until the Bounty Hunter caught up with them (or didn't, as the case may be).
I'll challenge the basic assumption: never mind the players, why can't the characters know they failed?
Maybe they waded into a stream to lose the trail, only to realize they left a broad swath of crushed plants behind them when they emerged to the other side. Nothing they can do about that, they have to carry on.
Maybe they intentionally smeared blood from a wound on the right tunnel in the subway, and proceeded down the left, but didn't notice until a few minutes later that they were steadily dripping blood, which left a clear trail.
Maybe the bounty hunter has mini tracking droids like the Inquisitor in Rebels, and they see one watching them before it ducks back behind a building.
The point is the character's knowing failure isn't alerting them to anything that derails your future actions. Anything the players plan to do to change their character's fate has no impact.
Consider all the movies you've seen where the protagonists realize their attempts aren't working, it's a pretty standard trope. I'd say the sense of dread that comes from the knowledge of failure is far more interesting and important than the mechanical hiding of details to separate character and player knowledge.